cannot pause while recording a voiceover...why?

Goal:
I am trying to record a voiceover (Record Slideshow) for a Keynote '09 presentation I already made.

Needs:
During the course of recording the voiceover, I will need to pause the recording occasionally, to clear my throat, to use the bathroom, feed the cat, what have you.

Attempted Solution:
In Keynote Help, under "Recording a Voiceover Narration" number 5 explains how to pause the recording. Press W, F, or B. You can also click the red recording indicator to pause.

Problem:
This is not working. Pressing W, F, or B does not pause the recording; it keeps recording. Also, I cannot click the red indicator, as there is no cursor on the screen anymore once recording begins. The cursor does not appear again until after Esc is pressed to stop and save the recording.

Does anyone know why I'm having this problem and how to pause voiceover recording?

Thanks for your help. ~ rebecca